Production of metal alkyls



May 31, 1966 K. ZIEGLER ET AL PRODUCTION OF METAL ALKYLS Original FiledJuly 25, 1961 INVENTORS KA R L Z/fG/f W( HERBERT Ef/M frz/HL @y MM] f@my TO NE s/S 3,254,009 PRODUCTION OF METAL ALKYLS Karl Ziegler andHerbert Lehmkuhl, Mulheim (Ruhr),

Germany; said Lehmkuhl assignor to said Ziegler,

Mulheim an der Ruhr, Germany Continuation of application Ser. No.129,195, July 25,

1961. This application Feb. 4, 1963, Ser. No..262,285 Claims priority,application Germany, Feb. 13, 1958, 6,509; Feb. 14, 1958, 6,510 52Claims. (Cl. 2114-59) This application is a continuation of applicationSerial No. 129,195, filed July 25, 1961, now abandoned, and which was acontinuation-impart of applications Serial No. 792,467, filed February1l, 1959, and 792,614, led February 1l, 1959, both now abandoned.

This invention relates to new and useful improvements in the productionof metal alkyls and particularly of alkyls of the metals lead, tin,antimony, bismuth, zinc,

cadmium, mercury. One preferred embodiment of the 4 invention concernsthe production of lead tetraalkyls.

In the production of metal alkyls use is frequently made, as alkylatingagent, of complex aluminum compounds having the grouping Me[Al(R)3-] inwhich Me is an alkali metal and R is alkyl. Thus mixtures of the desiredmetal alkyl with aluminum trialkyl are often obtained. .T he separationof the desired alkyl metal compounds is often connected withdifficulties because of the relative closeness of boiling points of thecomponents and/or the formation of hydrides and their deterioratinginfluence upon the alkyl compounds.

Such mixtures are for instance typically formed in the electrolyticproduction of metal alkyls and especially alkyls of the metals lead,tin, antimony, bismuth, zinc, cadmium, mercury.

Thus, when subjecting an alkali metal aluminum alkyl complex, as forinstance sodium or potassium aluminum tetraethyl to electrolysis usingone of these metals, such as, for instance lead, as the anode, thecorresponding metal alkyl compounds, such as tetraalkyl lead areformed.` Trialkyl aluminum is formed or liberated at the same time. Ifthe alkali metal aluminum tetraalkyl compound was a tetraethyl compound,triethyl aluminum is liberated which establishes its own independentliquid layer and does not intermix with the sodium aluminum tetraethylcomplex which under the conditions of reaction is normally present inmolten condition. The aluminum trialkyl, and particularly aluminumtriethyl, may thus be readily separated from the metal aluminumtetraalkyl complex. On the other hand, the separation of the aluminumtrialkyl and particularly of the aluminum triethyl from the other metalalkyl compounds, and particularly the metal ethyl compounds, which areformed during electrolysis, offers in most `cases considerabledifliculties. This is particularly'true for the mixture of leadtetraalkyl and aluminum trialkyl and most specifically for leadtetraethyl and aluminum triethyl because the boiling points of theseproducts are normally so relatively closely adjacent that separation bydistillation of mixtures of these materials is difficult if notimpossible. Furthermore, mixtures of tetraalkyl lead and aluminumtrialkyl and particularly mixtures of tetraethyl lead and aluminumtriethyl will decompose relatively readily because the lower aluminumtrialkyls and particularly aluminum triethyl will slowly degenerate withheat, being dissociated into dialkyl aluminum hydride and thecorresponding hydrocarbon. Thus, a mixture of tetraethyl lead andtriethyl aluminum will, with heat, form diethylaluminum hydride andethylene. Furthermore, such diethylaluminum hydride has a reducingeffect upon the tetraethyl lead converting the same to metallic leadwith the formation of ethane.

One object of the invention comprises an improvement United safes Patento 3,254,009 Patented May 31, 1966 JCC in the production of metal alkylswith an alkylating agent l A further object of the invention comprises anovel process for the separation of metal alkyls from aluminum-trialkylsin mixtures containing the same.

Still further objects of the invention comprises novel electrolyticprocesses for the production of metal alkyls.

The foregoing and still further objects of the invention will beapparent from the following description:

In accordance with the broadest aspect of the invention, a metal alkylproduction with the use of an alkyl radical supplying agent having thegeneral grouping Me[Al(R)3-] is effected, at a point between the metalalkyl formation and the separation of formed metal alkyl, in thepresence of a complex compound of the general formula: Me [Al(R)3OR] inwhich Me is an alkali metal of the group consisting of sodium andpotassium, R is an alkyl radical with up to 6 carbon atoms and R is anorganic radical selected from the group consisting of alkyl andcycloalkyl radicals to thereby substantially assure freedom from A1R3and to react said complex compound to form AIRZOR.

As shown below in greater detail, one limiting case of the metal alkylproduction in accordance with the invention is that in which thealkylating agent itself is said alkali metal alkyl aluminum alkoxycomplex compound. In that case the formation of trialkyl aluminum isavoided ab initio as for instance in an electrolytic alkylation in whichthe metal of the desired metal alkyl is used as anode and the saidcomplex compound constitutes the electrolyte. The other limitiing caseis that in which a mixture of the desired metal alkyl and aluminumtrialkyl (regardless of its derivation) is present and is to be used forthe metal alkyl production. In that -case the trialkyl aluminum iseliminated byreaction with said alkoxy complex compound i.e. it isconverted to an alkali metal tetraalkyl aluminum complex compound. Thisis accomplished in an electrolytic alkylation .in which the metal of thedesired metal alkyl is used as anode and an alkali metal aluminumtetraalkyl is employed as alkylating electrolyte. The trialkyl aluminumcontaining electrolysis product being acted with said alkoxy complexcompound for the elimination of the aluminum trialkyl. A further case ofmetal alkyl production in accordance with the invention is presented byconducting the alkylation, as for example electrolytic alkylation, withthe use of alkali metal tetraalkyl aluminum and said alkali metaltrialkyl aluminum alkoxy complex compound. In that case the productsresulting from the alkylation are substantially free from trialkylaluminum.

In laccordance with an embodiment of the invention a mixture containingaluminum trialkyl and an alkyl of a metal other than aluminum is reactedwith a complex compound of the general formula Me[Al(R')3OR], in whichMe is an alkali metal preferably sodium or potassium, R is an alkylradical up to 6 carbon atoms and advantageously a straight chain alkylradical with up to 4 and preferably 2-4 carbon atoms and in which R is amember of the group consisting of alkyl and cycloalkyl radicals, thealkyl radicals having advantageously 2 to 12 preferably 2 to 8 andespecially 4 carbon atoms. This reaction results in the substantialconversion of the trialkyl aluminum as for instance illustrated inaccordance with the following general equation:

The reaction thus results in the elimination of the trialkyl aluminumcompound and the formation of an alkali metal tetraalkyl aluminumcompound and an alkoxy aluminum dialkyl compound in admixture with thedesired metal alkyl compound. This mixture may now be further treatedfor the separation, such as by distillation of the desired alkali metalcompound. The invention in its application readily lends itself to theseparation of the alkyls and particularly lower alkyls of the metalslead, zinc, mercury, cadmium, antimony, bismuth and tin. Specificexamples are, for instance, lead tetraethyl, Zinc diethyl, mercurydiethyl, cadmium diethyl, antimony triethyl, bismuth triethyl, tintetraethyl, lead tetramethyl, .and the corresponding propyl and higherand lower alkyl derivatives of these metals. By a suitable selection ofthe residue OR the boiling points of the components of the mixturecontaining the desired metal alkyl may be lixed at any desired, suitabledifferential so that separation by distillation may be readilyaccomplished.

One electrolytic embodiment of the invention concerns the electrolyticproduction of alkyls of metals other than aluminum and particularly ofthe metals lead, tin, antimony, bismuth, Zinc, cadmium, mercury andespecially of lead tetraalkyls from complex compounds of the generalformula Me[Al(R)4] in which Me and R have the above given connotation.When proceeding in this manner, the metal, as for instance, lead, ofwhich the alkyl compound is to be produced is used as the anode togetherwith the alkali metal aluminum tetraalkyl compounds preferably presentin substantially molten condition as the electrolyte. The preferredelectrolyte is a mixture of potassium and sodium aluminum tetraalkylcompounds with the potassium component predominating. This increases theelectric conductivity of the electrolyte. There is anodically produced amixture of n mol aluminum trialkyl, Where n is the valence of the metalthe alkyl compound of which is produced, and lead tetraalkyl, such as,for instance 4 mol aluminum triethyl and lead tetraethyl which ispractically insoluble in the electrolyte mixture of, for instance,potassium and sodium aluminum tetraethyl with the Ipotassium componentpredominating. Such a mixture is, therefore, readily separable from theelectrolyte. The resulting mixture is, on the other hand, not readilyseparable by distillation into its components for the recovery of thedesired metal alkyls because, for instance, aluminum triethylandtetraethyl lead have boiling points that are closely adjacent. If,however, in accordance with the invention, there is added to thismixture 4 molecules of alkali metal alkoxyalu-minum-triethyl,immediately the following double reaction takes place:

In accordance with this reaction the tetraethyl lead is mixed with thealkoxy-aluminum-diethyl while the alkali metal aluminum tetraethyl, incase the sa-me is sodium, for instance, will separate at temperaturesabove 110 C. as a liquid layer while the same will be separated insubstantially solid form when operating at temperatures below 110 C. Aseparation of the mixture of tetraethyl lead and thediethyl-alkoxy-aluminum is then readily possible. Tetraethyl lead may beremoved by distillation, particularly with the suitable selection of theOR to assure an advantageous boiling point differential. Good resultsare thus obtained when there is selected for R a butyl radical. Insteadof first separating the alkali metal tetraalkyl aluminum electrolyte, asfor instance, aluminum tetraethyl sodium, the -mixture containing thethree components may be subjected to distillation for the removal of thetetraethyl lead whereupon the alkoxy aluminum dialkyl, such as thealkoxy-aluminum-diethyl, is distilled off or separated out by mechanicalseparation of nonmiscible phases. The sodium aluminum tetraethyl isreturned to the electrolyte and balances the amount of this materialused up in the electrolysis. The compound of `the general for-mulaROAl(C2H5)2 may then be worked up and reconverted into the compound asbelow set forth in detail in connection with an alternative embodimentof the invention.

An alternative electrolytic embodiment of the invention concerning theelectrolytic production of alkyls of metals other than aluminum andparticularly of lead, tin, antimony, bismuth, zinc, cadmium, mercury andespecially of lead tetraalkyls resides in the use as electrolyte of thesaid complex compound of the general formula Me[Al(R)3OR], using asanode, the metal of which the desired alkyl is to be formed. Whenproceeding in this manner, metallic potassium or preferably sodium aredeposited at the cathode, either as such or in the form of their alloys,while there is deposited at the anode a mixture of the alkyl compound ofthe metal of the anode together with n molecules of the .compound of theformula Al(R')2OR, n being the valence of the metal in the formed metalalkyl. In the case of, for instance, a 'lead anode and an alkali metalalkoxy aluminum triethyl, as the material in the electrolysis, thereresults at the anode a mixture composed of tetraethyl lead and fourmolecules of the compound Al(C2H5)2OR. The equation of the completechemical reaction involved in the electrolysis is in this case asfollows:

4Me [Al (C2H5) 3OR] -l-Pb-l-Electric Energy Besides the alkali metalthere is obtained as reaction product a mixture of alkoxy aluminumdialkyl compounds and the desired metal alkyl. This mixture, however.can easily be separated by distillation because of the higher boilingpoint of the aluminum alkoxy compound colmpared with aluminum trialkylcompound.

In this manner the alkyl of other metals, such as zinc, mercury,cadmium, antimony, bismuth, and tin, may lie conveniently obtained.Specific examples are thus, for instance, lead tetraethyl, zinc diethyl,mercury diethyl, cadmium diethyl, antimony triethyl, bismuth triethyl,tin tetraethyl, and the corresponding propyl and lower and higher alkylderivatives of these metals.

The compounds of the formula ROAl(R)2 do normally not possess thereactivity of aluminum trialkyls. Especially, they will not give thecharacteristic sodium uoride compounds of the aluminum trialkyls whichpossess an excellent conductivity. Accordingly the electrolyticconductivity of the complex compounds of the formula Me[Al(R)3OR] isrelatively bad so that when electrolyzing these compounds alone arelatively high current consumption Will have to be taken into account.In spite of the higher current consumption, the advantages of theprocess according to the invention are so considerable because of thefacilitated separability of the reaction products, that in comparisonthereto the disadvantages are unimportant.

The current consumption may be appreciably lowered when using as theelectrolyte a mixture of the complex compounds Me[Al(R)3OR] With complexcompounds of the general formula Me [Al(R)4] of which the latter possessa much better conductivity. For this reason there is to be used as theprincipal electrolyte a compound of the formula Me[Al(R)4] to which thecompound of the formula Me[Al(R)3OR] has been given as an addition.

When using a compound of the formula Me[Al(R)4] in which Me is sodium,it presents the considerable advantage that the electrolysis may be soregulated that metallic sodium can be obtained at the cathode in acontinuous liquid phase. The corresponding potassium compounds dopresent somewhat :nore difficulty in this respect in their cathodicseparation but do have a considerably higher current conductivity thanthe sodium com- For the practical operation of the electrolysis, it isimportant that the alkyl metal, such as the tetraalkyl lead, and in aspecific case, the tetraethyl lead is readily separable from thealkoxy-aluminumdiethyl or other dialkyl compound. By a suitableselection of the residue OR the boiling points of both components may bexed at any desired, suitable diiferential. In selecting OR, however, itmay be necessary to obtain an optimum cornpromise. OR should not be toosmall because otherwise the boiling point Will be too low. OR, on theother hand, shall not be too large because otherwise the ballast of theOR which is otherwise immaterial for the process becomes too large andthe conductivity of the complex electrolyte will be reduced. As compoundfor the production of, for instance, tetraethyl lead,thebutoXy-diethylaluminum may be used successfully. The 1:4 mixturePb(C2H5)4-(C2H5)2AlOC4H9 has the weight proportionate composition ratioof 323:632, that is, the same consists of approximately 1A of tetraethyllead and ZA of the butoXydiethyl-aluminum. A simple single and veryeasily entirely continuously conductible distillation will yield the-lead compound as the distillate and the lead free aluminum compound asthe residue. In this manner, the problem of the separation of thetetraethyl lead is solved in the most simple manner. Appropriately,there should be used in this case as an essential component of theelectrolyte preferably a compound It is, of course, understood thatdepending upon the reaction conditions other corresponding compounds maybe used in accordance with the invention.

An important advantage of the use of the compounds of the generalformula Me [Al(R)3OR] is that their mixtures with, for instancetetraalkyl lead, and especially tetraethyl lead and corresponding metalalkyls do not tend towards decomposition with heat.

The compounds of the general formula may be produced in various ways.One mode of production comprises the reaction of complex compounds ofthe formula Me[Al(R)4] with alcohols in accordance with the followingequation:

A further possibility is the reaction of aluminum trialkyl with sodiumor potassium alcoholates in accordance with the following equation:

A still further possibility is the careful oxidation ofaluminumtrialkyls with exactly 1/2 mol of oxygen whereby, however, onlycompounds are obtained in which RzR'. In accordance withan appropriateequation the reaction may be expressed as follows:

A suitable method for the production of compounds of the general formulaMe[Al(R)3OR] proceeds from the compound (R')2A1OR obtained at the anodeduring the electrolysis and the reaction of this compound withaluminumtrialkyl' and sodium or potassium in accordance with thefollowing equation:

"6 The aluminum obtained when proceeding in this manner may then beconverted in known procedure into aluminum trialkyl.

The best possibility for the purpose of producing or regeneratingcompounds of the general formula is the addition of alkali metalhydrides to the compounds of the general formula (R)2AlOR which areproduced 'at the anode and to react the addition products with ethyleneor olens of the type CnH2n+1CH=CH2 whereby in the case of ethylenecompounds, for instance, the following reaction takes place:

The practical execution of this embodiment may be effected :bytransferring the spent electrolyte, or, when operating with a diaphragmseparating the cathode and anode spaces, the catholyte, together withthesodium or potassium into a pressure reactor and, after the additionof the compoundl (C2H5)2AlOR obtained in the anode space, convert bytreatment with hydrogen into the cornpound Me[(C2H5)2AlH(OR)] and totreat the same with ethylene. The amount of alkali metal separated atthe cathode during the electrolysis is just suflicient for thisregeneration.

The treatment with ethylene is preferably carried out at 130 to 220 C.,particularly 150 to 200 C. with a pressure of up to 100 atmospheres,particularly 1 to 20 atmospheres.

In accordance with the above-described manner, a substantially closedcycle process may be carried out in accordance with the illustratedcycle for, for instance, tetraethyl lead:

, ing equation:

For this purpose the molten sodium complex compound is stirred withpowdered potassium chloride at about 120 C. whereupon the same is-decanted from undissolved sodium chloride. By use of less than one molof potassium chloride, in accordance with the above equation, anydesired ratio of sodium to potassium complex may be obtained.

Even with a relatively high potassium content, up to about potassiumcalculated on the whole alkali metal content, there will rst appear atthe cathode only molten sodium. Nevertheless, the conductivity can beincreased by the use of the potassium compound by about It is ofadvantage to so regulate the electrolysis conditions that liquid alkalimetal is separated at the cathode. This may be achieved by operating thecathode cell at at least 100 C. since sodium will melt at 96 C.Procedural conditions at which substantially pure or almost purepotassium would be separated at the cathode are not always as desirable.

The cathodically deposited sodium runs downwardly on the cathode as aliquid lm and can there easily be removed from the electrolytic device.

In a particularly advantageous and simple form of electrolysisarrangement, the anode and cathode are vertically concentricallyarranged tubes, the anode portion being composed of perforatedelectrically insulated material :behind which the metal to lbe dissolvedis arranged in the form of granules. The diaphragm is equally present intubular -for-m and is inserted between anode and cathode. For purposes`of the invention, the electrolysis itself may be thus constitutedrelatively simply. The anode space may be appropriately separated fromthe cathode space by a diaphragm. There is then preferably.

used an anolyte and catholyte of substantially the same composition. Theanolyte is advantageously saturated with (R)2A1OR so that uponelectrolysis, already the rst small amount of the metal alkyls and ofthe compounds of the formula (R)2A1OR which are formed will separate insubstantially liquid form.

A valuable composition of the electrolyte for the production of theethyl compounds of different metals, best expressed in mol percent byway of the ions in question, may be the following: Sodium 100 to 20%,potassium 0 to 80%, [(C2H5)4Al]- 95 to 50%, [(C2H5)3A1OR] 5 to 50%.Suitable electrolytes are, for instance, the following mixtures,indicated in mols:

Particular 4advantages are obtained in accordance with the invention bynot adding the alkali metal alkoxy aluminum compound to the electrolytebefore the `beginning of the electrolysis. Said alkali Imetal alkoxyaluminium compound is rather added preferably continuously to theelectrolyte during the electrolysis in such amounts suflicient for thedesired reaction, i.e. in such amounts as used up by the electrolyticreaction. In this manner it is possible to Work constantly with Imaximumconductivity. It is furthermore of advantage to maintain a relativelysmall distance from the cathode or anode and to select the same, forinstance, from 1 to 5 centimeters. Still further it is of advantage touse a current flow of electrolyte such that a relatively Weak current offlow passes from the cathode to the anode space which may be, forinstance,

accomplished by arranging'the electrolyte level in ther cathode spacehigher than that in the anode space. It is finally possible to operatewith electrolytic cells similar to those described in U.S. applicationsSerial Nos. 548,862 filed November 25, 1955, now Patent YNo. 2,985,568,and 740,623 led .lune 9, 1958, now Patent No. 3,069,334.

The separation of the metal alkyls produced in accordance with theinvention from the aluminum organic materials of the type AlRzOR `andfrom the electrolyte has been described here in its modus of operationas it is used in accordance with the lower alkyl compounds andespecially for tetraethyl lead and in which advantage is taken of thetwo layer separation of the anolyte in the course of the electrolysis,one of which layers then contains the principal portion of the metalalkyl produced in accordance with the invention. This two layerprocedure is not an absolute necessity, however. It is also possible toobtain by vacuum distillation of the total anolytes the desired metalalkyl from both the compound AlRZOR and the metal alkyl. This isindicated particularly for those cases where layer separation does notoccur which is especially true in the case, when the electrolytecontains compounds of the general formula Me[Al(R)3OR] in highconcentrations.

A particularly preferred method according to the inv Vention is carriedout by electrolyzing the mixture of the electrolyte compounds inacellunder vacuo, whereby the metal alkyl formed or the metal alkyltogether with the alkoxy aluminum dialkyls is continuously distilledott.

higher alkyl possess such a relatively low conductivity that currentconsumption is much too high.

The second described electrolytic embodiment of the invention possessesa number of considerable advantages. One of the principal benefits isthe relatively simple, readily immediate separability of the desiredmetal alkyls from the electrolysis `lay-products, which are formed inaccordance with the invention, which advantage is particularly true andof great value for the production of tetraalkyl lead such as tetraethyllead. A further advantage resides in the preferred embodiment involvingthe regeneration of compounds of the general formula Me [Al(R')3OR]however avoiding the necessity of making aluminum trialkyl from aluminumhydrogen and olens. This is especially important in the production ofethyl compounds which might otherwise lead to difficulties because inthe second stage of this method in accordance with the equation there isusually formed by the addition of a second ethylene some aluminum butylcompounds which may then be contained as impurity in the ethyl compoundproduced in accordance with the invention. On the other hand, thecomplex Me [Al(C2H5)3OR] lwill not further add any ethylene even in thepresence of an excess of ethylene and even at higher temperatures.

Furthermore, the method in accordance with the invention ischaracterized by a better space time yield in the hydrogenation phase ofthe cyclic process. The sodium hydride formation under pressure proceedsmore rapidly than the synthesis of the diethylaluminum hydride inaccordance with the equation A still fur-ther advantage resides in therelatively small current requirement of the electrolysis in View of therelatively high conductivity of the electrolyte. A most importantadvance, however, when proceeding in accordance with the method of theinvention, is the fact that by depositing an alkali metal preferablysodium at the cathode there a liquid metal is obtained, the separationand removal of which liquid metal can be effected without any difcultiesand does not involve any more any danger or problem of short circuitingWithin the cell.

On the other hand though the aggregate of the results obtained whenproceeding in the electrolytic preparation of the desired metal alkylsin accordance With said second described electrolytic embodiment are thesame as compared with that in accordance with said rst describedelectrolytic embodiment, the latter nevertheless also affords a numberof decided advantages. The elec- Itrolyte, in accordance With saidsecond described embodiment, has `a decidedly lower electricconductivity than the substantially pure alkali aluminum tetraalkylcomplex electrolyte in accordance with the first described embodiment.It is thus possible when proceeding, in accordance withthe latter, toelectrolytically produce the desired metal alkyl compounds withmaterially lowered energy requirements of the electrolysis cell for thesame yields or, alternatively, to obtain yields of about 50% higher withthe same energy.

Furthermore, in the case of certain alkyl compounds of some of themetals, and particularly the ethyl compounds of zinc and lead, themutual miscibility of the phase aluminum triethyl and methal ethyl, onthe one hand, molten alkali aluminum tetraethyl, on the other, is lessthan is normally the case for the miscibility of the phasesAl(OR)(C2H5)2, metal ethyl, on the one hand,

and the molten mixed electrolyte, in accordance with the method of saidsecond described electrolytic ,embodiment, on the other. It is possiblein this manner to reduce the residual content of the electrolyte of leador zinc in comparison to the method of said latter embodiment which willhave an advantageous veffect upon the course of the total process.

9 Example 1 3320 g. (220 mol) of sodium aluminum tetraethyl are stirredwith 740 g. mol) of potassium chloride for five hours at 150 C. Aftersettling of the sodium chloride which forms, the resultant equimolarmixture of sodium aluminum tetraethyl and potassium aluminum tetraethylis subjected to electrolysis While in molten condition.' The cathode isa copper cylinder and at a distance of about 1 centimeter a perforatedsynthetic resin cylinder of teon, polypropylene or high molecular Weightlow pressure polyethylene is positioned. A diaphragm consisting ofhardened lter paper or of a line textile or glass lter fabric isstretched over the synthetic resin cylinder. The `anode space issituated behind the diaphragm and is lled with lead spheres and any leaddissolved during electrolysis can be continuously replenished withadditional lead spheres in the anode space. The heating of theelectrolyte or removal of any current produced heat during theelectrolysis is eiected by circulating a liquid having a temperature ofabout 100 C. through the interior of the closed cathode cylinder. Heatinput or heat removal at the outer cylinder is so regulated that thetemperature within the anode space does not exceed about 70 C. Duringelectrolysis the temperature Within the anode space is preferablymaintained at about 100 C. while that within the anode space ismaintained at about 70 C.

The conductivity of the electrolyte mixture used is 4.5 10"2 (D cm.)1 at100 C. Current intensity is adjusted to about 20 A. corresponding to acell voltage of 2 volts.

The ow-oif from the anode space is adjusted to cc. per ampere hour sothat a reaction mixture with about lead tetraethyl runs olf. During thecourse of `12 hours, about 3,600 g. electrolyte are flown through theelectrolytic cell at 20 A. The electrolyte drained from the anode spaceconsists of two layers. ,The upper layer which mainly consists of sodiumaluminum tetraethyl is freed from small amounts of dissolved leadtetraethyl and aluminum triethyl under a vacuum of 0.5 mm. Hg and 120 C.and may subsequently be again used as electrolyte for a newelectrolysis. The distillate is combined with the lower layer which nowconsists of 700 g. lead tetraethyl and 1,020 g. aluminum triethyl. Theseparation of the mixture of lead tetraethyl and aluminum triethyl maybe effected in accordance with the process described in the followingexamples.

Example 2 A mixture of 700 g. lead tetraethyl and 1,020 g. aluminumtriethyl is stirred for 1 hour at 100l C. with 1,880 g. of sodium butoxyaluminum triethyl. |Upon termination of the agitation, the reactionmixture separates into 2 liquid layers. The upper layer is freed fromsmall amounts of dissolved lead tetraethyl under a vacuum of 0.5 mm. Hgand at 100 C. The distillation residueis v Example 3 Instead of the 1880g. sodium bu-toxy aluminum triethyl used in Example 2, the mixture of700 g. lead tetraethyl and 1020 g. aluminum triethyl formed according toExamplel may, for example, also be reacted with 2130 g. ofsodium-hexyl-oxy-aluminum triethyl Pure lead tetraethyl distills underthese condi-' or 2130 g. sodium isohexyl-oxy-aluminum 'triethyl HNa(C2H5)3A10oH2 l3-(CHmong A t...

or 2370 g. of sodium, isooctyl oxy aluminum triethyl n Na (C 2H5)3A1OCH2- -C 4H@ or 2620 g. of sodium decyl oxy aluminum triethyl- Na(C2H5`',AlOnCmHzl Working-up of the resulting reaction mixture is eifected ina manner analogously -to that of Example 2.

Example 4 3320 g. of sodium aluminum tetraethyl and 740 g. of potassiumchloride are stirred for 5 hours at 140 C. After settling of the sodiumchloride which forms the mixture comprising equivalent amounts of sodiumaluminum tetraethyl and potassium aluminum tetraethyl is subjected toelectrolysis in the apparatus described in Example 1 using an anode oflead. The procedure is the same as in Example 1 except tha-t the ow-offfrom the anode space Iis so adjusted that a reaction mixture with 10%lead tetraethyl is obtained, i.e. 30 cc. per ampere hour are withdrawn.After 6 hours, the total electrolyte stock has passed through theapparatus. The reaction mixture withdrawn consists of two phases. Theupper layer consisting preponderantly of potassium aluminum tetraethylis freed from lead tetraethyl and aluminum triethyl by distillation at amercury pressure of 0.5 mm. and C. The distilla'te is combined with thelower layer.

The separation of the lower layer consisting of 350 g. of leadtetraethyl and 510 g. of aluminum triethyl may be effected by theprocedures set forth in Examples 2 and 3.

The regeneration of the complex sodium alkoxy aluminum trialkylcompounds obtained in accordance with the preceding examples may beeffected by the following procedure described with reference to thebutoxy compound.

742 g.` (4.7 mols) Al(C2H5)2(OC4H9) are heated with 4.7 mols sodiumhydride under stirring in a nitrogen or argon atmosphere at to 140 C.for 1/2 hour. After this time the reaction mix is transferred in-to atwo liter autoclave filled with nitrogen and 50 to 60 atmospheres ofethylene are pressed on to the autoclave. The autoclave is then heatedwith rolling and shaking a-t to 150 C. until no pressure change isfurther observable. usually the case after about 4to 5 hours. Theautoclave content is pure Na[Al(C2H5)3(OC4H9)]. The yield is 990 g.(=100% of theory). This compound may again be used for separating leadtetraethyl from the electrolyte consisting of sodium aluminum tetraethyland potassium aluminum tetraethyl.

Example 5 N3 [A] (CaH'i) SOCI-12CH (02H5 l C4H9] and then distilled,preferably in a continuous lm evaporator in as high as possible alvacuum(0.1 mm. mercury) at 100 C. There are obtained 800 g. of leadtetrapropyl (=95% of theory).

Lead tetra-n-butyl can be obtained in an analogous A manner, it beingonly necessary to start with the butyl compounds corresponding to thepropyl compounds mentioned above.

This is The auxiliary materials needed for the process of the inventioncan be prepared as follows:

(l) Monoalkoxy aluminum dialkyls, are prepared by allowing 1 mol of thealcohol to react with 1 mol of the corresponding aluminum trialkyl.

(2) The complex compounds are prepared in a similar manner by addingdropwise 1 mol of the alcohol into the corresponding sodium aluminumtetraalkyls or by the procedure described in Example 4 with respect tothe regeneration.

Example 6 The procedure is the same as in Example 1 except that zinc,cadmium, tin, antimony and bismuth, preferably in granular form, areused as the anode metal instead of lead. When using mercury as the anodemetal, the anode space of the apparatus described in Example 1 isprovided with superposed channels of an insulating material Example 7 Amixture of 123 g. of zinc diethyl and 228 g. of aluminum triethyl isstirred 'at 100% C. together with 364 g. of sodium ethoxy raluminumtriethyl 'for' 30 minutes. Then the Zinc diethyl is distilled offfrornthe mixture at a mercury pressure of 100 mm. and 80 C. Thedistillation residue consis-ts of 2 phases. The upper layer is ethoxyaluminum diethyl and the lower layer consists of sodium aluminumtetraethyl with a small amount of dissolved ethoxy aluminum diethyl.

Example 8 A mixture of 235 g. of tin tetraethyl and 456 g. of aluminumtriethyl is stirred at 100 C. for 1/2 hour together with 840 g. ofsodium butoxy aluminum triethyl. The reaction mixture which forms isfreed from the tin tetraethyl at a mercury pressure of mm. and 90 C.(measured in the liquid). The distillate is pure tin tetraethyl and theyield is 230 g. (=98% of theory).

Example 9 With the same procedure set forth in Example 8, mixture of 170g. of cadmium diethyl (boiling point, 54 C. at 11 mm. mercury) and 228g. of aluminum triethyl; 258 g. of mercury diethyl (boiling point, 60 C.at 10 mm. mercury) and 228 g. of aluminum triethyl; and 209 g. ofantimony triethyl (boiling point, 60 C. at 10 mercury) and 342 g. ofaluminum triethyl are separated.

Example 10 The procedure is the same as in Example 5 except that anodesof zinc instead of lead are used. The mixture of 330 g. of Zinc dipropylIand 1370 g. of aluminum tripropyl separated by distillation from theresidual electrolyte is stirred by distillation from the residualelectrolyte is stirred at 100 C. for 1/2 hour together with 2710 g. ofNa[(CaHq)3AlOCH2CH(C2H5)C4H9] and then distilled at a mercury pressureof 0.1 mm. and 100 C., the distillation being most preferably carriedout in a continuously operating lm evaporator. The yield is 320 g. (=97%of theory) of zinc dipropyl.

Example 11 By `a procedure analogous to that of 'Example 10, a mixtureconsisting of 314 g. of mercury dibutyl, 396 g. rof

aluminum tributyl and 1000 g. of unchanged sodium aluminum tetrabutylobtained by electrolysis in accordance with Examples 1 and 6,respectively, can be separated. 700 g. of sodium octyl oxy aluminumtributyl is added to the mixture which is then distilled under as highas possible a vacuum of 10*2 mm mercury and at 100 C. to separate puremercury dibutyl. The yield is 290 g. (94% of theory). V

Example 12 Na[A1(C2H5)s(OC4H9) l -l-CzHs 10 mol (=1660 g.) NaAl(C2H5)4are dissolved in three liters of dry and -air-free benzene and are thenadmixed drop-wise in an inert atmosphere in a six liter three-neck flaskunder vigorous stirring with 10 mol (=740 g.) nbutanol. The solution ofthe complex salt heats up until the benzene comes to a obil. Theaddition of the butanol is so adjusted that the reaction mixture willboil under slight reflux. The solvent is removed by vacuum vaporizationafter the completion of the reaction. The resulting complex compoundNa[Al(C2H5)3(CO4H9)] will solidify upon cooling The yield is 2100 g. oftheory). The electric conductivity is 2.2 l0301cm51 at 100 C.

The complex compound is filled, preferably in molten condition into anelectrolysis arrangement as shown on the appended drawing. Thisarrangement is provided with an opening 1 for introducing theelectrolyte, a further opening 2 for adding the metal the alkyl compoundof which is intended to be produced, means 3 for withdrawing theseparated alkali metal and an outlet 4 for the reaction mixture from theanode space. 5 is the overflow for the cathode liquid and 6 that for theanode liquid. Between the cathode 8 and the anode metal 11 is arranged aperforated cylinder of an insulating material 7 and a diaphragm. Heat--ing and cooling means 9 are provided Within the cathode space to heatthe cathode liquid to the appropriate temperature while the anode liquidis maintained at the temperature desired by means of the heating device10 using a recirculated medium. The cathode Iis a copper cylinder 8 land at a distance of about 1 centimeter a perforated synthetic resincylinder 7 of polypropylene or high molecular weight low pressurepolyethylene is positioned. A diaphragm consisting of hardened lterpaper or of a line textile or glass filter fabric is stretched over thesynthetic resin cylinder The anode space is situated behind thediaphragm and is filled with lead sp-heres 11 and any lead dissolvedduring electrolysis can be continuouslyreplenished through opening 2with -additional lead spheres in the anode space The heating of theelectrolyte or removal of any current produced heat during theelectrolysis is etfected by a liquid 9 having a temperature of about 100C. in the interior of the closed cathode cylinder. Heat input or heatremoval at the outer cylinder is so regulated that the temperaturewithin the anode space does not exceed about 70 C. During electrolysisthe temperature within the cathode space is preferably maintained atabout 100 C. while that within the anode space is maintained at about 70C. Current intensity is adjusted to about 15 A. at 30 volts betweenelectrodes which corresponds to an anodic current intensity of 4 A./dm.2and a cathodic current intensity of 10 A./dm.2. The cathodically formedsodium will flow away from the cathode into the lower cathode -spacefrom which it may be removed in molten condition from time to time. Theflow away from the anode space is so adjusted that a reaction mixturewith about 10% lead tetraethyl runs o whereby the inflow into thecathode space is so adjusted that the liquid level within the cathodespace is by `about 4-5 centimeters higher than that within the anodespace. In the course of about 5 hours, the entire electrolyte has ownthrough the electrolysis cell. By distillation in vacuo at 0.5 to 0.3mm. mercury and 40 to 42 C., at first the tetraethyl lead can beseparated from the Al(C2H5)2(CO4H9) and the remaining complex compound.The aluminum diethylbutoxy is separated by distillation at in vacuo at0.5 mm. merphases.

' ethylene are pressed on to the autoclave.

400 g. (=2.5 mol) AI(C2H5)2(OC4H9) are heated with 58.2 g. (=2.5 gramatom) sodium and 96.2 g. (=0.84

mol) Al(C2H5) 3 wit-h stirring in an inert atmosphere, While at' atemperature of about 180 C. The aluminum is per-v mitted to deposit fromthe hot melt and the supernatant liquid is separated.

The newly formed, as well as the complex salt which has remainedunchanged during the electrolysis may now be again used for furtherelectrolysis.

Example 13 10 mol (=1660 g.) Na[Al(C2H5)4] are dissolved in three litersof dry and air free benzene and are then admixed in an inert `atmospherein a six liter ask as described in Example l2 with 5 mol (=370 g.)n-butanol. After completion of the reaction the benzene is removed byvaporization and there is obtained a mixture of 5 mol (=830 g.)Na[Al(C2H5)4] and 5 mol :1050 g.) Na[Al(C2H5)3(OC4l-I9) The conductivityof this mixed electrolyte is 2Q*1cm.1 at 100 C.

This electrolyte is subjected to electrolysis in the arrangementdescribed in accordance with Example 12 between a copper cathode and alead anode at the conditions of temperature there set forth. At avoltage of 9 volts between electrodes a current passage of A. isobtained which corresponds to an anodic current intensity of 5.3 A./dm.2and a cathodic current intensity of 13 A./cm.2. The cathodically formedsodiu-m is removed in liquid condition from time to time and the effluxfrom the anode space is so adjusted that a reaction mixture with 20%tetraethyl lead flows o'. By adjusting appropriately the inflow into thecathode space a liquid level differential between cathode and anodeliquid of about 4 centimeters is maintained. During the course of about6.3 hours, the entire electrolyte has passed through the electrolysiscell.

The tetraethyl lead is removed from the reaction mix -by distillation at40 C. and 0.5 to 0.3 mm. mercury.

The yield of tetraethyl lead is 360 g. (=95% of theory). The lead freedistillation residue separates into two The upper is practically pureA1(C2H5)2(OC4H9) which may be converted into Na[A1(C2H5)3(OC4H9)] by thefollowing operation:

A1(C2H5)2(OC4H9) -i-NQH* Na [Hal(C2H5)2(OC-1H9) l Na[Hal(C2H5)2(OC4H9) l+C2H4 Na [A1(C2H5)3(OC4H9)] 742 g. (=4.7 mol) Al(C2H5)2(OC4H9) areheated with 4.7 mol sodium hydride Linder stirring in a nitrogen orargon atmosphere at 120 to 140 C. for 1/2 hour. After this time thereaction mix is transferred into a two liter autoclave filled withnitrogen and 10 atmospheres of The autoclave is then heated with rollingand shaking at 170 C. until no pressure change is further observable.This is usually the case after about 4 to 5 hours. The autoclave con- 14tent is pure Na[Al(C2H5')3(OC4H9)]. The yield is 990 g. of theory).

- Example 14 Electrolysis is carried out as described in Example 13using the same mixed electrolyte. After separation of the tetraethyllead by vacuum distillation and preparation of the upper layer ofA1(C2H5)2(OC4H9) from the complex salt, the 742 g. (=4.7 mol) butoxyaluminum diethyl are placed into a nitrogen filled 2 liter autoclavetogether with 4.7 gram atoms (=1O8 g.) sodium, which has formedcathodically. Thereupon 250 atmospheres of electrolyte hydrogen arepressed on and the autoclave is heated underv rolling to to 140 C. Afterabout 7 to 8 hours, there is usually no further pressure reductionobservable. Excess hydrogen is then blown off and about 5 atmospheres ofethylene are pressed on. The reaction proceeds quantitatively at 200 C.and is completed after about 4 to 5 hours in accordance with thefollowing equation: N21[A1(C2H5)2H(OC4H9) l -i-CzHr) lNa[A1(C2H5)3(OC4H9)l The newly formed electrolyte is then admixed withresidual electrolyte and the cycle can begin anew.

Example 15 (a) 5 mol (=830 g.) sodium aluminum tetraethyl are heatedunder stirring to to 150 C. in an inert atmosphere together with 6 mol(=447 g.) of dry potassium chloride. The reaction i is completed inabout three to four hours. After settling of the sodium chloride, themelt of potassium aluminum tetraethyl is decanted from the sodiumchloride. The yield of K[Al(C2H5)4 is 820 g. (=90% of theory).

(b) 5 mol (830 g.) sodium aluminum tetraethyl are admixed with 5 moln-butanol as described in Example l2. The resulting sodium butoxyaluminum triethyl is then mixed with the potassium aluminum tetraethylobtained in accordance with the reaction (a) and there is therebyobtained a mixed electrolyte, the electrolytic conductivity of which at100 C. is 4.5 102S21cm.1. In the electrolyses of this electrolyte theprocedure set out in Example 12 is followed. The electrolysis waseffected for 5 hours at 15 A. The mixed electrolyte of potassium andsodium compound will cathodically separate under these conditions asubstantially pure sodium. The yield of sodium is quantitative. Theseparation of tetraethyl lead is effected by distillation in high vacuumas described in Example 13. The conversion of the butoxy aluminumdiethyl into sodium butoxy aluminum triethyl may be effected inaccordance with the procedure set out in Example 12 to 14. The yield is210 g. of lead tetraethyl (=93% of theory).

Example 16 When proceeding in the same manner, set forth in Example 13,except that instead of lead there are used as anodic materials themetals: Zinc, tin, antimony, bismuth, cadmium, and mercury respectively,the ethyl compounds of these metals were obtained as set forth in thefollowing tab e:

Anode Current Anode, Met. Alkyl Dist. Temp. Yield Remarks IntensityA./d1n.2

Zn 15 4 Zn(CzH5)z 24-26/l0mm 91 Sn 15 4 SI1(C2H5)4 64/10mm 85 Diaphragmnot necessary.

15 4 Sb(CzH5)s 60-65/20mrn 96 15 4 Bi(C2H5)3 60/10mm 95 15 4 Cd(C2H5)z64 81 5 4 H8(C2H5)2 82 (1% 1 For the production oi the mercury diethylthere were used in the anode space ot the electrolysis arrangement thcliquid mercury.

1 5 Example 17 1140 g. of aluminum triethyl are diluted with l liter ofdry and air-free hexane. Then 1580 g. of n-decyl alcohol are addeddropwise with stirring. The heat of the reaction causes the hexane toboil vigorously. Therefore, a reflux condenser is used.` The hexane issubsequently withdrawn under a moderate vacuum. There is left the decyloxy aluminum diethyl as rather iiuid oil.

This is the most simple process to produce a compound of this type if anelectrolysis has not yet been carried out. The following prescription`is then equally applicable to a produce freshly prepared in this manneras well as to a product recovered from the electrolysis.

The 2420 g. of the decyl oxy aluminum diethyl obtained are mixed with 1liter of a 24 wt. percent sodium hydride suspension in decaline or witha corresponding amount of a similar suspension of different sodiumhydride content and the entire mixture is filled into a pressure vessel.Ethylene of 20 to 50 atmospheres is pressed on with stirring and themixture is heated to 170 C. The ethylene is absorbed and the pressure ismaintained at a constant level by pressing on additional ethylene untilan ethylene absorption does no longer occur. This is the case afterabout 6 hours. A sample drawn of the reaction mixture, when carefullyhydrolized, should now furnish only ethane but no hydrogen. In mostcases, however, a small residual content of hydrogen of about 0.5% willbe observed in the gas obtained in the hydrolysis. This is, however, notdisturbing. They pressure is released, the temperature is allowed todrop somewhat to about 130 C., the pressure vessel is provided with adescending condenser, and a vacuum is applied. Now the decalineintroduced by the sodium hydride suspension distills. Finally, thetemperature is increased again to 150 to 170 C. and the pressure isreduced to a few mm. mercury. There are left in the pressure vesselabout 2900 g. which may be removed under nitrogen. The complex compoundis a very viscous oil which does not show a tendency to crystallize.

The cathode and anode spaces of the electrolysis cell described inExample 12 lirst contain sodium aluminum tetraethyl in molten state.Sodium decyl oxy aluminum triethyl or, optionally, .sodium isohexyl oxyaluminum triethyl is allowed to iiow continuously into the anode spacefrom above at a rate which is tobe adapted to the current flowingthrough. The current circuit is closed as this addition starts. Anamount of l1 g./hr. of sodium decyl oxy aluminum triethyl (or 8.9 g. ofsodium isohexyl oxy aluminum triethyl) is allowed to iiow in per ampereof current flowing through. At the bottom of `the anode space, thereseparates a liquid layer consisting of a mixture of decyl oxy aluminumdiethyl (or isohexyl oxy aluminum diethyl) and lead tetraethyl, whichcontains rather exactly 25% (30%) by Weight of lead tetraethyl. Thislayer is continuously withdrawn at a rate that the main electrolyte, themolten alkali aluminum tetraethyl, remains unchanged in the anode space.The electrolyte level in the cathode space should be higher by about 4centimeters than that in the anode space. Both of the spaces arepreferably provided with overows and sodium aluminum tetraethyl,preferably in molten state, is continuously introduced into the cathodespace at a rate that only a small amount flows over. The amount owingover from the cathode space is returned into the stock of the sodiumaluminum tetraethyl.

Some sodium aluminum tetraethyl will also llow over in the anode space,this amount being the higher the more permeable the diaphragm is. Thisportion of the sodium aluminum tetraethyl is not capable of beingdirectly returned into the stock since it contains lead. It must irst befreed from lead tetraethyl -by heating to aboutv 100 Q. under vacuum.For an electrolysis cell of the size set forth in Example 12, about 10to 30 A. are allowable, i.e., on an hourly base, to 330 g. of sodiumdecyl oxy aluminum triethyl (or 89 to 267 g. of sodium isohexyl oxyaluminum triethyl) can be converted and to 360 g. of the mixture of leadtetraethyl and decyl oxy aluminum diethyl (or 100 to 300 g. of themixture of lead tetraethyl and iso-hexyl -oxy aluminum diethyl) can berecovered, from which the lead tetraethyl is distilled off at a mercurypressure of about 1 mm. and a bath temperature up to 100 C. f

The regeneration of the decyl oxy aluminum, diethyl compound into thecomplex sodium decyl oxy aluminum triethyl is effected by the procedureset forth in the iirst paragraph of this example.

Example 18 In this example, the electrolysis cell used simply consistsof a vacuum-resistant steel container, in the center of which a cathodeof a copper plate and on both sides of the cathode at a distance ofabout 1 to 2 centimeters therefrom anodes consisting of thick leadplates are arranged. The cathode is connected with the steel shell ofthe container to provide metallic conduction. Moreover, the cathode isof sufficient length as to contact the bottom of the container whilebetween the container and the lower end of .the anode a free space ofabout 20 centimeters is left. The container is tilled under nitrogenwith an electrolyte consisting of 80% of potassium aluminum tetraethyland 20% of sodium aluminum tetraethyl. Moreover, a larger quantity ofsodium aluminum ethoxy is prepared as follows: 1140 g. of aluminumtriethyl are mixed under lnitrogen with 680 g. of completely dry andalcohol free sodium ethylate and the mixture is heated to about 100 C.until a clear melt has formed. Upon cooling, the melt solidies at 80 C.

By means of a descending cooler, the container is connected with acooled receiver tank and a vacuum pump. The container is heated to to140 C. and evacuated to less than 0.1 mm. mercury if possi-ble. Now,through a special line mounted at the container and provided with avalve, the molten sodium aluminum ethoxy triethyl iS allowed to flow inslowl)l and the current is applied in that moment where the content ofthis compound added at least has reached 5% in the contents of thecontainer. The current is now adjusted to a current density of 10 to 30A./dm.2 and now the second electrolyte is allowed to iiow incontinuously at a rate corresponding to the current density, i.e. 6.78grams per ampere hour.

There distills continuously a mixture of lead tetraethyl v and diethylethoxy aluminum, i.e. 3 g. of lead tetraethyl in mixture with 4.85 g. ofethoxy diethyl aluminum. per ampere hour. In this arrangement, thecomplex electrolyte containing potassium and sodium remains practicallyunchanged in the container, and only the intlowing sodium ethoxyaluminum triethyl is decomposed. The molten sodium accumulates incorrect amount, i.e. 0.86 grams per ampere hour. The electrolysis may beoperated until the sodium level in the container is suiciently high asto cause a short circuit with the lead anode. Of course, the sodium mayalso be dissolved out of the container in liquid state after temporaryinterruption of the vacuum and the current supply. The distillate isseparated into lead tetraethyl (boiling point, 38 C./l mm.,) and ethoxyaluminum `diethyl (boiling point, 72 C./ l mrn.) using a column whichneeds not be very eflicient. The sodium formed in the electrolysis isfurther processed in conventional manner to form sodium hydride which isadded to the electrolyte for regeneration as described above (Examples12-14).

Example 19 1560 g. of aluminum tripropyl are mixed under nitro- |17 melthas fo'nmed The result-ant complex compound which is sodium hexoxyaluminum tripropyl is mixed with an equimolar amount of sodium aluminumtetrapropyl and the electrolyte mixture obtained is subjected toelectrolysis in accordance with the procedure set forth in Example 12.

With a current of 10 amperes passing through, the riiow- 01T from ltheanode space is so adjusted that a .reaction mixture with '10% of leadtetrapropyl runs off. After 5 hours, about 1500 g. of electrolyte hasown through the electrolysis cell. The reaction mixture is 'freed fromlead tetrapropyl at a mercury pressure of 0.1 mm. and 100 (measured inthe liquid). The yield of lead tetrapropyl is 160 g. (=90% of theory).

Example 20 2780 `g. of sodiumY aluminum tetrabutyl are dissolved in 3liters of dry benzene. To the solution, 790 g. of ndecanol-l are slowlyadded dropwise with vigorous stirring. After the total amount is added,the benzene solvent is distilled off at 120 C. (measured in the liquid).There is obtained a mixture of equimolar amounts of the complexcompounds sodium aluminum tetrabutyl and sodium decyloxy aluminumtributyl.

rllhis mixed electrolyte is subjected to electrolysis between a coppervcathode and a lead anode using the apparat-us described in Example 12.The procedure is otherwise the same as set out in Example 12. Theresulting reaction mixture with 10% of lead tet-rabutyl is freed fromlead tetrabutyl at a mercury pressure of 10-3 mm. and 120 C. (measuredin the liquid). The yield of lead tetrabutyl is 80% of ltheory.

Example 21 The equimolar mixture of sodium aluminum tetrapropyl andsodium hexyl oxy aluminum tripropyl obtained in accordance with Example19 is subjected Ito electrolysis by the procedure set forth in Example12 using an anode of antimony.

With a cur-rent of 10 A. owing through, 310 g./hr. of the reactionmixture containing about 10% of antimony tripropyl are Withdrawn. Afterhours, about 1.7 liters of electrolyte have ilown through the cell. Thereaction mixture is freed from antimony tripropyl at a pressure of 3 mm.mercury and 90 C. (measured in the liquid).

The yield of antimony tripropyl is 135 g. (=89% of theory).

Example 23 The mixed electrolyte produced in accordance with Example 20is subjected to electrolysis by the procedure set forth in Example 20using zinc granules as the anode material. With a current intensity of10 A., 33 g. of reaction mixture are withdrawn from the anode space perampere hour. This corresponds to a content of zinc dibutyl of about 10%.

'Ilse reaction mixture obtained is freed 'from zinc dibutyl at a vacuumof 0.1 mm. mercury and 90 C. (measured in the liquid). The yield of zincdibutyl is 3.0 g. per ampere hour (=82% of theory).

Example 24 A mixture of `267 g. (=1 mole) Pb(CH3)4 and 288 g. (=4 moles)Al(CH3)3 obtained by electrolysis of NaAMCHa)4 18 with the use of a leadanode is stirred for 1 hour at 80 C. with 672 g. (=4 moles) ofNa(CH3)3AlOC4H9. The reaction mixture consists of a liquid phase inwhich the insoluble NaAl-(CH3)4 formed is suspended. The solids areseparated by ltration in an inert gas atmosphere. The solids areidentified by analysis as pure NaAl(CH3)4 and may thus be used aselectrolyte in another electrolysis operation. The ltrate which consistsof -a mixture of Pb(CH3)4 and (CH3)2A1OC4H9 is separated lby fractionaldistillation in a 50 cm. Vigreux column at about 100 mm. Hg. The rstfraction obtained comprises 250 gms. Pb(CH3).,y corresponding to 93.5%of the theory. vAfter withdrawal of a small intermediate vfraction o-fabout 20 to 30 ml. which contains both lead alkyl and aluminum alkyl,the residue from distillation is substantially free from lead alkyl andmay be reconverted into the complex compound Na(CH3)3AlOC4H9 byprocesses known per se. The intermediate fraction is preferably combinedwith the next batch to be separated.

Example 25 If 'the separation of fthe mixture of 267 gms. of Pb(CH3)4and 288 gms. of Al(CH3)3 obtained by electrolysis is effected byreaction with 784 gms. of

Na(CH3)3AlOnC6H13 with 896 gms. of

Na(C H3)3A1O CH2-C H-C 4H9 or with 1008 gms. of Na (CH3)3AlOnC10H21likewise effected at C. in place of the reaction with Na (CH3 `',AIOC4H9the lead tetramethyl can be easily, i.e., without a column, distilledfrom the ltrate at about mm. Hg and a bath temperature of 70 to 80 C.after filtration and recovery of the NaAl(CH3)4. The yields of lead-tetramethyl arel R an alkyl radical, said complex compound being otherthan an alkoxy derivative, the improvement which comprises effectingsuch production, at a point Ibetween the metal alkyl formation and theseparation of formed metal alkyl, in the presence of a complex compoundof the general formula: Me[Al(R)3OR] in'which Me is an alkali metal ofthe group consisting of sodium and potassium, R is `an alkyl radicalwith up to 6 carbon `atoms and R is an organic radical selected from thegroup consisting of alkyl and cycloalkyl radicals to therebysubstantially assure freedom .from AlR3 and to react said complexcompound to form AlRzOR.

Improvement in accordance with claim 1 in which R represents an alkylradical with four carbon atoms.

3. In the production of metal alkyls, the improvement according to claim1 in which lsaid trialkyl 'aluminum is substantially continuouslyproduced in said material and vis reacted with said compoundsubstantially as it is produced.

4. In the production of alkyls of metals selected from the groupconsisting of lead, tin, antimony, bismuth, zinc, cadmium and mercuryfrom a material containing such metal alkyl and aluminum trialkyl, theimprovement comprising reacting said material with a compound of thegeneral formula: Me[Al(R)3OR] in which Me is an alkali metal of .thegroup consisting of sodium and potassium, R is a straight chain alkylwith up to 6 carbon atoms and R is an organic radical selected from thegroup consisting of alkyl and cycloalkyl radicals and separating saidmetal alkyl compound from the reaction lproduct formed.

19 5. In the production of metal alkyls the improvement according toclaim `4, in which said material is substantially continuous-ly suppliedfrom the electrolysis, with one of said metals as anode, of alkali metaltetraalkyl aluminum, in which said metalalkyl separating issubstan-tially continuously effected by distillation, and in which saidalkali metal tetraalkyl aluminum is recycled to said electrolysis.

6. In the production of metal alkyls the improvement according to claim'5, in which the alkyl radical of said trialkyl aluminum is the same asis defined by R, and in which said anode metal is lead.

7. Improvement according to claim 4, in which R is an alkyl with from2'to 12 carbon atoms.

8. Improvement according to claim 4, in which R is an alkyl with from 2to 8 carbon atoms.

9. Improvement in accordance with claim 4, in which R represents analkyl radical with four carbon atoms.

10. Improvement according to claim 4, in which R `represents a straightchain alkyl with up to 4 carbon atoms.

11. Improvement in accordance with claim 4, in which R' represents theethyl radical.

1 2. Improvement according to claim 4, in which said metal of the metalalkyl compound is lead, in Which R represents the ethyl radical, and inwhich R represents an -alkyl radical.

13. In the production of metal alkyls the improvement according to claim4 in which said separating is effected by distillation.

14. In the process for the production of metal alkyls, the improvementwhich comprises subjecting to electrolysis, while using as an anode 'ametal selected from the group consisting of lead, tin, antimony,bismuth, zinc, cadmium, and mercury, an electrolytey comprising a com--pleX compound of the general formula Me[Al(R)3OR] containing admixedtherewith an amount of a compound 'having the general formulaMe[Al(-R')4] suflicient to increase its electric conductivity, in saidgeneral formulas R representing a member selected from the group consisting of alkyl and cycloalkyl, Me representing a member selectedfromthe group consisting of potassium and' sodium, and each R'representing a straight chain alkyl radical containing from 26 carbonatoms, to thereby form at the anode an alkyl compound of said `anodemetal together with an alkoxy aluminum dialkyl compound of the generalformula Al\(R')2OR, while depositing substantially metallic alkali metalat the cathode, and separ-ating said' alkyl compound from said alkoxyaluminum dialkyl compound.

15. Improvement according to claim 14 in which said alkoxy aluminumdialkyl compound is regenerated to said complex compound by reactingsaid alkoxy aluminum dialkyl compound with hydrogen and olefin and amem- -ber selected from the group consisting of sodium and potassium andin which the regenerated compound is returned to said electrolysis.

16. Improvement according to claim 15 in which said cathodicailydeposited alkali metal is used ,for said regeneration with aluminumtrialkyl.

17. Improvement in accordance With claim 14 in which said alkoxyaluminum dialkyl compound is regenerated 'to said complex compound byreacting said alkoxy aluminum dialkyl compoundvwith alkali metalhydride, and

. treating the product, formed in said reaction, with olen and in whichthe regenerated compound is returnedy to said electrolysis.

18. Improvement according to claim 17in which said olefin is ethylene,in which said anode metal is lead, in which R is an ethyl radical, inwhich said alkali metal hydride is sodium hydride and in which saidsodium hydride is obtained by hydrogenation of the cathodically producedsodium.

19. Improvement according to claim 14, in which R is an alkyl with from2 to 8 carbon atoms.

20 20. Improvement in accordance with claim 14, in which R representsa-n alkyl radical with four carbon atoms.

21. Improvement according to claim 14, in which R represents a straightchain alkyl with up to 4 carbon atoms.

22. Improvement in accordance with claim 14, in which R represents theethyl radical.

'23. Improvement in accordance with claim 14 in which said anode metalis lead, and in which R is the ethyl radical.

24. Improvement according to claim 14 in which R is an alkyl radicalwith from 2 to 12 carbon atoms.

25. Improvement according to claim 14 in which saidanode metal is lead,in which R is the ethyl radical and in which R is -an alkyl radical.

26. Improvement according to claim 14 in Which said compound of theformula Me [Al(R)4] is in the form of a mixture of the potassium andsodium compound.

27. Improvement according to claim 14, in which said alkoxy aluminumdialkyl compound is regenerated to said complex compound -by reactingsaid alkoxy` aluminum dialkyl compound with' sodium and hydrogen underpressure and treating the product formed in said reaction' with olensand inv which the -regenerated compound is returned to saidelectrolysis.

28. Improvement according to claim 14, in which for 100 to 20 molpercent sodium and 0I to 80 mol percent potassium, each calculated tothe whole alkali metal content,.there is used to 50 mol percent of theionof the formula [(C2H5)4Al]- and 5 to 50v mol percent of the ion ofthe gener-al formula [(C2H5)3Al`OR]-.

29. Improvement according to claim 14, in which said complex compound isadded continuously to said electrolyte during the electrolysis in suchan amount as it is used up in the electrolysis.

30. Improvement according to claim 14,A in which, as said Mel[Ali(R)4]is used a mixture of potassiumr aluminum tetraalkyl and sodiumaluminumtetraalkyl, which mixture has `been produced -by reacting 1 molsodium aluminum tetraalkyl with less than 1 mol potassium chloride.

31. Improvement according to claim 14 in which R is the ethyl radical,in which R is analkyl radical, in Which -anodically produced liquid' ispermitted to separate into layers one of which containsl said metalalkyl compound and. said alkoxy aluminum dietlhyl compound, and in whichsaid metal alkyl compound is recovered from said last-mentioned layer.

32. Improvement in` accordance with claim 14, in which the electrolysisis carried out ata temperature suf,- ciently high to assure the cathodicseparation of' alkaliV metal in substantially liquid form.

33. In the process in the production of metal alkyls,v

the improvement which comprises subjecting the electrolysis, while usingas an anode a metal' selected,- fromr the group consisting of lead, tin,antimony, bismuth, zinc, cadium and mercury, an electrolyte comprising acomplex compound of the general formula containing admixed therewith` anamount ofa compoundI of the general formula Me [Al(R')4] suiicientV toincrease;

'its electric conductivity, in said general-formulas R repre- 34.Improvement according to claim 33, in which a phase containingsubstantially a mixture of said metal alkyl compound and said alkoxyaluminum dialkyl compound is mechanically separated from the remainingelectrolyte and said metal alkyl compound is separated from said alkoxyaluminum dialkyl compound by distillation 1n vacuo.

35. Improvement according to claim 3 4, in which the remainingelectrolyte is purified from traces of said metal alkyl compound bydistillation in vacuo and at elevated temperature.

36. Improvement according to claim 33, in which the separation of saidmixture is etected by distillation in vacuo.

37. Improvement according to claim 33, in which a mixture of said metalalkyl compound and said alkoxy aluminum dialkyl compound is separatedfrom the remaining electrolyte by distillation in vacuo.

38. Improvement according to claim 33, in which said alkoxy aluminumdialkyl compound is separated `from the remaining electrolyte bydistillation in vacuo.

39. Improvement according to claim 33, in which said metal alkylcompound is separated from said alkoxy aluminum dialkyl compound and theremaining electrolyte by distillation in vacuo during the electrolysis`of the mixture of said irst and said second electrolyte compound.

40. Improvement according to claim 33, in which said metal alkylcompound and the alkoxy aluminum dialkyl compound is separated from theremaining electrolyte by distillation in vacuo during the electrolysisof the mixture of said first and said second electrolyte compound.

41. Improvement according to claim 33, in which R is the ethyl radicaland the electrolyte during the electrolysis saturated with the alkoxyaluminum diethyl compound.

42. In the process for the production of metal alkyls, the improvementwhich comprises subjecting the electrolysis, while using as an anode ametal selected from the group consisting of lead, tin, antimony,bismuth, zinc, cadmium andmercury, an electrolyte comprising a complexcompound having the general formula Me[Al(R)3OR] containing admixedtherewith a suicient amount of a compound having the general formulaMe[Al(R)4] to increase its electrical conductivity, in said generalformulas, R representing a member selected from the group consisting ofalkyls and cycloalkyl radicals, Me representing an alkali metalselectcdfrom the group consisting of potassium and sodium, and R representing astraight chain alkyl radical containing from 2 to 6 carbon atoms, ytothereby form at the anode an alkyl compound of said anode meta-l,together with an alkoxy aluminum dialkyl compound of the generalform'ula Al(R)2OR, separating said metal alkyl compound and ysaid alkoxyaluminum dialkyl compound from the remaining elec- 22 trolyte bydistillation, adding to said alkoxy aluminum dialkyl compound sodiumhydride, treating the resulting product formed with an olefin to therebyproduce said complex compound and adding `the complex compound vformedto the electrolyte.

high to assure the cathodic separation of alkali metal in substantiallyliquid form.

48. Improvement according to claim 42 in which for 100 to 20 mol percentsodium and 0 to 80 mol percent potassium, each calculated `to the wholealkali metal content, there is used 95 to 50 mol percent of the ion ofthe formula [(CZH5)4A1] and 5 to 50 mol percent of the ion of thegeneral formula [C2H5)3A1OR].

49. Improvement according to claim 42 in which the intermingl'ing of thecathode liquid with the anode liquid is inhibited without impeding thecurrent transfer in the electrolyte.

50. Improvement according to claim 42 in which the electrolysis iscarried out under vacuo without any separation of the cathode liquidfrom the anode liquid.

51. In the production of metal alkyls of metals other than aluminum froma material containing such metal alkyl and trialkyl aluminum, theimprovement which comprises reacting said trialkyl aluminum with acompound of the general formula: Me[Al(R)3OR] in which Me is an alkalimetal of the group consisting of sodium and potassium, R' kis an alkylradical with up to 6 carbon atomsy and R is an organic radical selectedfrom the group consisting of alkyl and cycloalkyl radicals to therebyconvert said trialkyl aluminum to an alkali metal tetraalkyl aluminumand separating metal alkyl from the reaction product formed.

52. Improvement according to claim 4, wherein said reaction is carriedout in an electrolysis cell wherein said metal alkyl and said aluminumtrialkyl are produced by electrolysis.

References Cited by the Examiner UNITED STATES PATENTS 8/1958 Ziegler etal. 204-59 X 7/ 1960 Giraitis 204--59

14. IN THE PROCESS FOR THE PRODUCTION OF METAL ALKYLS, THE IMPROVEMENTWHICH COMPRISES SUBJECTING TO ELECTROLYSIS, WHILE USING AS, AN ANODE AMETAL SELECTED FROM THE GROUP CONSISTING OF LEAD, TIN, ANTIMONY,BISMUTH, ZINC, CADMIUM, AND MERCURY, AND ELECTROLYTE COMPRISING ACOMPLEX COMPOUND OF THE GENERAL FORMULA M$(A)(R'')3OR) CONTAININGADMIXED THEREWITH AN AMOUNT OF A COMPOUND HAVING THE GENERAL FORMULAM$(A)(R'')4) SUFFICIENT TO INCREASE ITS ELECTRIC CONDUCTIVITY, IN SAIDGENERAL FORMULAS R REPRESENTING A MEMBER SELECTED FROM THE GROUPCONSISTING OF ALKYL AND CYCLOALKYL, M$ REPRESENTING A MEMBER SELECTEDFROM THE GROUP CONSISTING OF POTASSIUM AND SODIUM, AND EACH R''REPRESENTING A STRAIGHT CHAIN ALKYL RADICAL CONTAINING FROM 2-6 CARBONATOMS, TO THEREBY FORM AT THE ANODE AN ALKYL COMPOUND OF SAID ANODEMETAL TOGETHER WITH AN ALKOXY ALUMINUM DIALKYL COMPOUND OF THE GENERALFORMULA AL(R'')2OR, WHILE DEPOSITING SUBSTANTIALLY METALLIC ALKALI METALAT THE CATHODE, AND SEARATING SAID ALKYL COMPOUND FROM SAID ALKOXYALUMINUM DIALKYL COMPOUND.